Hardcopy of pybind11 instead of using git submodules (#552)

* removed pybind as submodule
* added hardcopy of pybind11 2.10.0
* rename pybind11 folder to avoid conflicts when changing branch

Co-authored-by: Dhanya Thattil <dhanya.thattil@psi.ch>

libs/pybind/tests/pybind11_tests.h

@@ -0,0 +1,85 @@
+#pragma once
+
+#include <pybind11/eval.h>
+#include <pybind11/pybind11.h>
+
+namespace py = pybind11;
+using namespace pybind11::literals;
+
+class test_initializer {
+    using Initializer = void (*)(py::module_ &);
+
+public:
+    explicit test_initializer(Initializer init);
+    test_initializer(const char *submodule_name, Initializer init);
+};
+
+#define TEST_SUBMODULE(name, variable)                                                            \
+    void test_submodule_##name(py::module_ &);                                                    \
+    test_initializer name(#name, test_submodule_##name);                                          \
+    void test_submodule_##name(py::module_ &(variable))
+
+/// Dummy type which is not exported anywhere -- something to trigger a conversion error
+struct UnregisteredType {};
+
+/// A user-defined type which is exported and can be used by any test
+class UserType {
+public:
+    UserType() = default;
+    explicit UserType(int i) : i(i) {}
+
+    int value() const { return i; }
+    void set(int set) { i = set; }
+
+private:
+    int i = -1;
+};
+
+/// Like UserType, but increments `value` on copy for quick reference vs. copy tests
+class IncType : public UserType {
+public:
+    using UserType::UserType;
+    IncType() = default;
+    IncType(const IncType &other) : IncType(other.value() + 1) {}
+    IncType(IncType &&) = delete;
+    IncType &operator=(const IncType &) = delete;
+    IncType &operator=(IncType &&) = delete;
+};
+
+/// A simple union for basic testing
+union IntFloat {
+    int i;
+    float f;
+};
+
+/// Custom cast-only type that casts to a string "rvalue" or "lvalue" depending on the cast
+/// context. Used to test recursive casters (e.g. std::tuple, stl containers).
+struct RValueCaster {};
+PYBIND11_NAMESPACE_BEGIN(pybind11)
+PYBIND11_NAMESPACE_BEGIN(detail)
+template <>
+class type_caster<RValueCaster> {
+public:
+    PYBIND11_TYPE_CASTER(RValueCaster, const_name("RValueCaster"));
+    static handle cast(RValueCaster &&, return_value_policy, handle) {
+        return py::str("rvalue").release();
+    }
+    static handle cast(const RValueCaster &, return_value_policy, handle) {
+        return py::str("lvalue").release();
+    }
+};
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(pybind11)
+
+template <typename F>
+void ignoreOldStyleInitWarnings(F &&body) {
+    py::exec(R"(
+    message = "pybind11-bound class '.+' is using an old-style placement-new '(?:__init__|__setstate__)' which has been deprecated"
+
+    import warnings
+    with warnings.catch_warnings():
+        warnings.filterwarnings("ignore", message=message, category=FutureWarning)
+        body()
+    )",
+             py::dict(py::arg("body") = py::cpp_function(body)));
+}